1. Field of the Invention
The present invention relates to a mobile telecommunication terminal, and more particularly to a system and method for tracing a location of the terminal in a service area.
2. Background of the Related Art
One conventional system for tracing the location of a mobile telecommunication terminal involves mounting a global positioning system (GPS) receiver in the terminal and then determining location by analyzing a signal received from a low-earth-orbit satellite. A second conventional system traces the location of a terminal using a network of a wireless telecommunication system. These methods will now be explained.
FIG. 1 shows the first conventional system, which traces the location of a mobile telecommunication terminal by analyzing a signal from a low-earth-orbit satellite. This system includes a satellite receiving unit 10 which receives satellite signals transmitted from a plurality of universal GPS satellites (1˜N). Location information included in the received signals and time deviations of the received signals, are then used to trace the location of the terminal. In this system, the GPS satellites (1˜N) and the satellite receiving unit 10 require a substantial amount of locking time at first. Also, sending/receiving of the satellite signal is disturbed by adjacent architectures and a receiving sensitivity of the satellite signal is very weak. Accordingly, a location of the mobile telecommunication terminal is inaccurately recognized and much cost is required.
FIG. 2 shows the second conventional system, which traces the location of the mobile telecommunication terminal using a network of a wireless telecommunication system. This system includes a plurality of base stations 22-1, 22-2, . . . 22-n which receive a predetermined signal transmitted from the mobile telecommunication terminal 21. A location calculation unit 23 then calculates a location of the terminal using location information according to the predetermined signal from the plurality of base stations and reception time deviation between the received signals. The calculated result is provided to the mobile telecommunication terminal 21.
The second conventional system described above performs location tracing based on a distance difference between the mobile telecommunication terminal 21 and the base stations 22-1, 22-2, . . . 22-n. As a result, a base station located far from the terminal has difficulty in receiving a signal necessary to calculate a location, since the base station has a weak receiving sensitivity for the signal transmitted from the terminal. In order to solve this problem, it has been proposed to increase a strength for transmittance force of the corresponding terminal. However, it has been shown that a terminal having an increased transmittance force does not easily recognize the signal transmitted from a base station located far from the terminal. That is, in the second conventional system for tracing a location of the mobile telecommunication terminal using a network of a wireless telecommunication system, even if the GPS receiver does not have to be mounted in the mobile telecommunication terminal, an error range for a location of the terminal is substantial.